Inflation signaling device



Feb. 13, 1940. E. w. GRIFFITH INFLATION SIGNALING DEVICE Filed March 1, 1939 2 sheets-sheet 1 y. w e

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gwn/MM ar/ WGH/77770, QQ-M7 www Feb 13 1940- E. w. GRIFFITH INFLATION SIGNALING DEVICE Filed March l, 1959 Patented Feb. 13, 1940 UNITED STATES PATENT OFFICE 4 Claims.

This invention relates to inflation signaling devices, and has more particular reference to 'certain improvements in the construction disclosed in my co-pending application Serial Number 177,814, led December 2, 1937.

The primary object of the present invention is to provide, in a signaling device of the kind noted above, an improved pressure-operated switch for controlling the signaling circuit oi' each tire.

More particularly, the present invention contemplates the provision of such a pressure-operated switch which will not be uni'avorably affected by the momentum of the wheel when traveling at a high rate of speed, thereby overcoming a serious objection found with a pressure-operated switch utilizing a Bourdon tube as disclosed in my above-mentioned prior application.

A further object is to provide an improved pressure-operated switch of the above kind, wherein simple and eiiicient means is provided for regulating the tension of the movable contact so that the switch may be adjusted to close the signaling circuit at any desired predetermined al pressure.

Another object of the present invention is to provide a pressure-operated switch of the above kind which is extremely simple and durable in construction, as well as inexpensive to manufacture, eiilcient in use, and adapted for ready and convenient installation.

Still another object of the present invention is to provide a novel arrangement of contact ring and means for readily mounting the same on and insulating the same' from the hub of the wheel.

Another object is to provide a novel arrangement, mounting and relationship of contact rings, pressure switch, and means for connecting the pressure-operated switch with the inilation valve y of the tire.

With the above general objects in view, the invention consists in the novel form, combination and arrangement of parts hereinafter more fully described, shown in the accompanying drawings and claimed.

In the drawings: y

Figure 1 is a detail transverse section of a wheel equipped with certain elements forming part of the present signaling device.

Figure 2 is an enlarged detail section clearly ,illustrating the construction and mounting of the brush which engages the contact ring forml ing part of the construction shown inV Figure 1.

Figure 3 is an enlarged detail view, partly in section, illustrating the tting employed in the connection between the tire inflation valve and one end -of the conduit which connects with the pressure-operated switch.

Figure 4 is an end elevation of the pressureoperated switch, drawn on an enlarged scale.

Figure 5 is a longitudinal section taken on the plane of line 5 5 of Figure 4.

Figure 6 is a section on line 5-6 of Figure 4.

Figure 7 is a fragmentary plan view of the body of the pressure-operated switch, looking toward the inner or rear face ci said body; and

Figure 8 is a diagrammatic view illustrating the circuits of a systemin which the present signaling device is associated with each oi' the four wheels of the motor vehicle.

Referring in detail to the drawings, the pres--1 ent signaling device includes a pressure-operated switch or circuit closer consistingof a disk-like body 5 having a ,central circuit recess i in the outer face4 thereof and provided with a central 20 rearwardly projecting hollow stem 1 adapted for connection with the tire whose state of ination is to be indicated. Bolted as at 8 to the margin of the body 5 is a clamping ring Q, and a flexible elastic diaphragm I0 is clamped between the 25 margin of the body 5 and the ring 9 so as to provide an air pressure chamber, between the diaphragm and the recessed portion 6 oi the body 5, communicating with the passage through the stem 1. A movable contact arm II consisting of 30 an elongated strip of spring metal is bolted at one end to the ring 9 as at I2, and this contact extends diametrically of the diaphragm I0 and has a free end portion oi angular form extending across the edges of the ring 9 and body 5 8l as at I3 and inwardly behind the adjacent portion of body 5 as at I4. Loosely iitted within the ring 9 is a disk I5 ci insulating material which is disposed between the contact arm II and diaphragm III so as to position said contact arm o entirely out of engagement with ring 9 and body 5 when the proper pressure exists within the tire connected with the stem 1, as shown clearly in Figure 5. The desired tension is placed upon the contact arm II by means of a tension device consisting of a strip I6 of spring metal extending across the contact arm II near its attached end and anchored at one end to the ring 9 by bolting or the like as at I1. The other end of tensioning strip I6 is provided with a boss I8 into 'which 50 is adjustably threaded a screw I9 extended through the opposite side of body 5, diaphragm In and ring 9 as shown clearly in Figure 6. 'I'he holes in the body 5 and ring I which receive the screw I9 are countersunk as at III to receive the 55 flanged ends of a binding sleeve 2| positioned through vthese holes. Obviously. by rotating the screw I9, the tension of strip I5 may be adjusted so as to correspondingly tension the contact arm II, and suitable means is provided for maintaini inner face of the head of screw I8 as indicated clearly in Figure 6. In other words, this is simply a ratchet arrangement which prevents the screw I8 from accidentally turning-as commonly practiced in many arts, for analogous purposes, although permitting intentional or manual turning and adjustment of said screw I8. The tensioning strip I 6 is insulated from the contact arm Il by means of a thin block of insulating material 24 having a groove in one face receiving the contact arm I I as shown in Figure 6, and another groove in the other face receiving the tensioning strip I6 as shown in Figure 5.

It will be apparent that when the pressure in the tire connected with the stem 1 of this pressure-operated switch becomes greater than required, the contact arm I I will move outwardly to engage its terminal end I4 with the body 5 so that a signaling circuit may be completed to warn the driver of this fact. Likewise, should the pressure in the tire be lowered beyond that required for proper inflation of the tire, the contact arm II may engage the ring 9 and thereby close the signaling circuit to serve as a warning to the driver. It will be particularly apparent that the pressure-operated switch is of very rugged or durable and compact construction and is not sensitive or readily unfavorably affected by centrifugal force. Accordingly, the switch will operate efficiently and will not be materially affected by the momentum of the wheel when traveling at a high rate of speed. t

The pressure-operated switch is mounted upon the radial wall of and within a brake drum 25 attachedl to a radial flange 26 of a wheel hub 21 carrying an ordinary demountable wheel body 28 having a rim 29 on which the tire 30 is mounted. As shown clearly in Figure 5, the stem 1 of the pressure-operated switch extends through the radial wall of brake drum 25 and the body 5 abuts the inner face of such wall and is clamped thereagainst by means of a nut 3I threaded on the stem I and against the outer face of said wall. vln

this way, the pressure-operated switch is readily rigidly fastened in place with the body thereof within the brake drum 25, and with the stem 1 of the pressure-operated switch extended toward the inflation valve 32 of the tire 30. 'In order to connect the stem 1 with the inflation valve 32, the latter is provided with an attached three-way fitting 33 as shown more clearly in Figure 3,one branch of said tting being screwed on the valve 32, another branch being coupled to the stem 1 by means of a conduit 35, and the remaining branch being adapted for connection with an inflation hose and provided with a check valve 34 and a removable cover or cap 35. The ends of conduit 35, which may consist of a short piece of flexible hose, are provided with quick detachable couplings which may be readily engaged with or detached from the stern 1 on the fitting 32 so as to permit ready demounting of the wheel body 28 with respect to the hub 21 and drum 25 as required in the art, the wheel body 28 being provided with an opening as shown in Figure 1 through which the vconduit 35 extends. This provides for ready assembly or separation of parts whenever same is required for repairs or the like.

Mounted upon the hub 21 within the drum 25 is a contact ring 31 rotatable with the wheel and insulated from the hub 21 by means of a bushing 38 of insulating material. This bushing has a 'flange on one end to prevent anyv possible contact of the ring 31 with the hub flange 26 when fittedl on the hub 21 as shown. The ring 31 has a driving fit on the bushing 38 so that rotation of contact ring 31 with hub 21 is insured when the parts are assembled. A brush 38 is constantly pressed against the contactring 31 and carried by a holder 40 mounted in an opening of the closure disk 4I of the brake drum 25. This closure disk is stationary and suitably iixed upon the axle or axle housing 42 as is well known in the art. As shown clearly in Figure 2, the brush holder 40 preferably consists of a tube 43 having a plurality of nuts 44 threaded thereon, the closure disk 4I being tightly clamped between adjacent ones of to place the brush 38 in the signaling circuit.

The contact ring 31 is electrically connected to contact arm II of the pressure-operated switch by means of a wire 48 whose ends may be respectively soldered to the outer face of contact ring 31 and to the contact arm I I.

Referring to the diagram of Figure 8, the brush I4 of each wheel may be connected by a wire 50 with one side of a lamp or other warning signal 5I, the other side ofsaid lamp or signal being connected by wire 52 with one side of a storage battery 53. The ignition switch 54 of the motor vehicle may be interposed in the wire 52 between the battery 53 and the lamp or signal 5I. In this way, the signal circuit will be broken when the ignition circuit of the motor vehicle, generally indicated at 55, is broken, the signal circuit-being closed when the ignition circuit is closed by switch 54.

It will be understood that each of the wheels of the vehicle is provided with a pressure-operated switch, contact ring, brush holder, and connection between the pressure-operated switch and the tire, as described. The brush 38 of each wheel may be connected with a separate lamp or signal 5I as shown, or all of the brushes may be connected to single lamp or signal depending upon whether or not an indication or warning is relmired with respect to each individual wheel.

In operation, the switch 54 is closed, and if the tires of all of the wheels are properly inflated, the contact II of the pressure-operated circuit closer will be disengaged from their associated parts 5 and 9, so that the signal circuits will bebroken and the signals will be inoperative. However, should any one of the-tires be over or under infiated,the contactI I .of the circuit closer associated with the wheel equipped with that tire will be engaged with either the body 5 or ring 8 so that the associated signal circuit will be closed and its signal 5I rendered operative. Thus, the driver will be warned of the under iniiation or over inlation of the tire. By adjusting screw I9, the

tension of contact Il may be properly regulated `so that the circuit will not be closed unless the pressure in the tire exceeds or goes below the correct inflation pressure of the tire in question. Thus, the device may be installed upon wheels having tires requiring different pressures of innation, by merely adjusting the tension of con- -tact il instead of providing special pressure-operated switches for each individual installation. While the pressure-operated switch is well adapted for use in inflation signaling devices, it will be apparent that the same is adapted for general use in any apparatus or device requiring a switch operable by iluid under pressure.

It is believed that the construction and operation of the present invention, as weil as the advantages thereof, will be readily understood and appreciated by those skilled in the art. It will also be appreciated that the invention is susceptible of many minor changes in details of con'- struction without departing from the spirit and scope oi the invention as claimed.

What I claim as new is:

1. In a tire inflation signaling device, a pressure-operated switch comprising a disk-like body having a central inlet stem provided with external threads, a nut threaded on said stem for clamping the switch to a support with the stem extending through an opening in the latter, a clamping ring bolted to the margin of said body, a flexible diaphragm having its margin clamped between said ring and said body and providing a chamber in communication with the bore of said stem, a resilient contact strip attached at one end to oneside of said clamping ring and having its other end free and extending around the edges of said body and said clamping ring and then inwardly at the inner side of said body, an insulating disk iltted in said ring between said diaphragm and said contact strip, and means for adjusting the tension of said contact strip.

2. In a tire iniiation signaling device, a pressure-operated switch comprising a disk-like body having a central inlet stem provided with external threads, a nut threaded on said stem for clamping the switch to a support with the stem extending through anopening in the latter, a clamping ring bolted to the margin of said body. a iiexible diaphragm having its margin clamped l0 between said ring and said body and providing a chamber in communication with the bore o! said stem, a resilient contact strip attached at one end to one side of said clamping ring and having its other end free and extending around the edges of said body and said clamping ring and then inwardly at the inner side of said body, an insulating disk tted in said ring between said dia-` phragm and said contact strip, a resilient tensioning strip extending across said contact strip and secured at one end to said clamping ring, and means for adjustably drawing the Aother end of said tensioning strip toward said clamping ring for regulating the tension of said contact strip.

3. In a tire inflation signaling device, a pressure-operated switch comprising a disk-like body having a central inlet stem provided with external threads, a nut threaded on said stem for clamping the switch to a support with the stem extending through an opening in the latter, a clamping ring bolted to the margin of said body. a flexible diaphragm having its margin clamped between said ring and said body and providing a chamber in communication with the bore of said' stem, a resilient contact strip attached at one end to one side of said clamping ring and having its other end free and extending around the edges of said body and said clamping ring and then inwardly at the inner side of said body, an insulating disk fitted in said ring between said diaphragm,

and said contact strip, a resilient tensioning strip extending across said contact strip and secured at one end to said clamping ring, means for ad- Justably drawing the other end of said tensioning strip toward'said clamping ring for regulating the tension of said contact strip, and a thin insulating block interposed between said contact strip and said tensioning strip, said insulating block having a groove in one iace receiving the contact strip and a further groove in its other face receiving said tensioning strip.

4. A pressure-operated switch comprising a disk-like body having a central inlet stem, a clampng ring bolted to the margin of said body, a flexible diaphragm having its margin clamped between said ring and said body and providing a chamber in communication with the bore oi said stem, a resilient contact stripattached at one end to one side of said clamping ring and having its other end free and extending around the edges of said body and said clamping ring and then inwardly at the inner side of said body, an insulating disk tted in said ring between said diaphragm and said contact strip, and means for adJusting the tension of said contact strip.

EARL W. GRIFFITH. 

